I think that wouldn't be too difficult to allow us to specify the URL to a custom stylesheet. All elements have their ID's, so that wouldn't make it hard to re-style something.If you are not willing to implement such feature, I'd like to know why. Thank you.

The code may make decisions in places based on the current css parameters of certain DOM elements so there may be unintended consequences to that (which I can't debug for you). That said, you do have access to the wrapper's HEAD section in the Web Settings group. And any file you put in the designated "Web folder" will get served by request.